Grinding ring



Ja n. 14, 1941 5 V DER PYL 2,229,019

GRINDING RING Filed Sept. 5. 1939 Patented Jan. 14, 1941 GRINDING RING Edward Van der Pyl, Holden, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application September 1 Claim.

The invention relates to grinding wheels.

One object of the invention is to provide a grinding wheel of simple construction in which the abrasive is diamonds. Another object of the invention is to provide a construction for the manufacture of a diamond grinding ring using small blocks without any screws or like fastening devices. Another object of the invention is to provide a construction for building up an abrasive l ring out of blocks containing diamonds so that all of the diamond material may be used up in abrading. Another object of the invention is to provide an eflicient diamond grinding wheel of large diameter which can be easily and quickly is manufactured." Other objects will be in part obvisas or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the several steps and my relation and order of eachof said steps to one or more of the others thereof, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claim.

at In the accompanying drawing in which is shown one of various possible embodiments of the me elianical features of this invention:

Figure 1 is a plan view of a grinding ring constructed in accordance with the invention.

30 Figure 2 is a cross sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a cross sectional view on an enlarged scale taken on the line 3-3 of Figure 1.

Figure 4 is a plan view on a large scale of a unit 35 abrasive block or insert.

Figure 5 is an end view of the abrasive block or insert on the same scale as Figure 4.

Figure 6 is a fragmentary plan view of the grooved ring before the abrasive blocks are inserted, shown on an enlarged scale as compared with Figures 1 and 2, showing construction lines.

Figure 7 is a plan view of a device for inserting the abrasive blocks showing the device in operation. 5 Referring first to Figures 2 and 6 I provide a bronze ring II). This may readily be manufactured by first manufacturing a right circular cylindrical ring and then grooving it to provide grooves II as shown in Figure 6. These grooves 50 I I are shaped to receive abrasive blocks or inserts I2 shown in Figures 4 and 5. The grooves II are all alike and similarly oriented. That is to say their inner edges I3 projected are all tangent to a given circle which is coaxial with the circle 55 of the ring III. Likewise their outer edges II are 5, 1939, Serial No. 293,398 (Cl. 51-209) all tangent to a given circle which is coaxial with the circle of the ring Ill. The grooves are thus nonradial and they are also undercut.

The abrasive blocks I 2 fit in the grooves I I and I therefore their shape is the same as that of the grooves II. Referring to Figures 4 and 5 the edges I5 and I6 are not parallel; thus the blocks I2 are slightly tapered. Furthermore the edges I9 and 20 are not parallel either; thus the blocks I2 are tapered in another dimension. The blocks I2 have inner ends 2| and outer ends 22 which are segments of cylindrical surfaces.

The blocks I 2 may be formed in a suitable mold and readily withdrawn from the mold because of the fact that they are tapered. The blocks I2 5 are abrasive blocks and in the preferred form of my invention are made in accordance with my Reissue Patent No. 21,165. The abrasive preferably is diamonds and the bond preferably is copper with an additional metal adapted to impart frig ableness to the copper. For example I may provide an alloy of around 80% copper and tin by weight. Preferably I provide copper and tin powders and mix the copper and tin powders with finely divided diamond abrasive for example in 25 the proportions of 25% abrasive by volume to 15% bond by volume. I then charge this mixture into the mold and press under a pressure of the order of ten tons to the square inch. I then remove the formed abrasive block I2 from the mold and sinter it in a furnace supplied with hydrogen flame curtains at a temperature of about 700 C. This sintering although it does not melt the copper sinters it and the tin together into an alloy which alloy has brittle or friable characteristics. The result is anabrasive block I2 the abrasive of which is diamonds and the bond of which is a friable metal bond in accordance with my Reissue Patent No. 21,165. Abrasive bodies so made have been found to have excellent characteristics in many 40 practical grinding operations, particularly for the grinding of the hard carbides such as tungsten, molybdenum and boron carbides.

The foregoing may be widely varied and so far as this invention is concerned metal bonds having 5 different characteristics may be used although I prefer to use a friable bond. In particular an abrasive article may bemade from any of the mixtures included in my Reissue Patent No. 21,165 with excellent results in practice.

Having formed a sufilcient number of abrasive blocks or inserts I2 to fill all the grooves II in the bronze ring I0, I force them into the grooves with pressure in any suitable manner. For example the ring I0 may be placed over a cylinder upon which it just fits and the blocks is may he forced into the grooves irons the outside with a special tool. Such a tool is shown in Figure "I and comprises a slideway block 25 in which is a slide 26 having an end 21 which fits the end of the block i2. The slideway block .25 is placed against the periphery of the ring to with a block 82 in the slide 28 and then the slide 28 may he hit with a hammer which will insert the block 62 into the appropriate groove i i. This operation may be repeated until all the grooves ii are filled with inserts or blocks l2.

Referring to Figure 2, the ring it is mounted upon any suitable support by means of screws or bolts extending into threaded holes 3t formed in the ring iii, or any other suitable method of mounting may he adopted. The ring should be rotated in the direction of the arrow (Figure i) so that the grinding pressure will tend to force the blocks i2 into the grooves ii in the ring iii. It is noted that the taper is such that it is dimcult to force the blocks further than the final position as shown. The dove-tailed shaping of the blocks It keeps them from coming out of the grooves it.

This grinding wheel or abrasive ring is made up without the use of any holding plates iron: at number of abrasive blocks and a very tight union with the ring it is achieved. The ring it may he made of bronze, brass, or aluminum, or in certain casw it may be desirable to make the ring it out of steel. During grinding the lands 3i between blocks 82 will wear down as the hlcclss' l2 wear down and thus all of the abrasive hiocks it may be used up. In fact the blocks 52 and lands 3% start flush and end the same way at the com clusion of the useful life of the grinding ring. Owing to the fact that the abrasive is diamonds, however, the ring will last for a great many grinding operations.

One advantage of the invention is that the molding equipment for forming the ehrasive'portion is very simple and the abrasive parts themselves are very small and can he handled in a small furnace. The final article, however, may he relatively large,

in size. The ring it! is of such shape that it can m easily machined. For example a hollow cylindrical casting can he turned and ground on the inside and outside, then cut into rings with s cutting-016E tool on a lathe end the grooves it sesame formed with a shapes equipped with a suitable indexing device. in this way a ring iii of great accuracy can be formed at small cost.

By reason of being made of metal, the ring it is resilient or malleable enough to allow the inserts E2 to be driven in to a tight fit and it is also strong enough to hold the inserts without danger of the lands 5! breaking off. At the same time the bond of the blocks i2 is hard. enough and tough enough so that driving the blocks into place does not deform them excessively.

as shown, every groove is of the same shape, also every land is of the same shap and also every block is of the same shape. But the lands need not be, and two or more sizes or shapes of blocks and grooves could he used. i prefer that the blocks be all oriented inthe same angular direction. "Uniformity of sizes and shapes of the groovesand of the blocks gives the advantage of simplicity and it is preferred the entire article he in balance.

it will thus be seen that there has been provided by this invention an article and e method which the various objects hereinahove set forth together with many thoroughly practical sdvem tages are successfully achieved. its many possible emleodimenm may he made oi the shove venticn and as many changes might made the embodiment shove set forth, it is to he us derstood that all matter hereinheiore set forth, or shown in the accompanying drawing, is to he interpreted as iliustrstive and not in e. limiting sense.

I claim: i

A composite abrasive article comprising a metal ring, integral lands formed in a face of 5 id ring leaving grooves therehetvveen, the grooves bein undercut and non-redial and the grooves being to.- pered in the plane oi the ring, and dovetailed tsmred metal bonded abrasive blocks the size oi the grooves inserted in said grooves with a tight fit, all of said blocks and grooves being oriented in the same angular direction, the sole support for theabrasive hioclrs lceing the aforesaid inteeral lands whereby the abrasive blocks can be driven into the grooves and being metal bonded will not he fractured.

efnwsnn vars one PYL. 

